Clamping and elevating apparatus for machine tools



w. G. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS May 27, 1958 ll Sheets-Sheet 1 Filed Aug. 9, 1956 w gINVEI'VTOR. him AT TOEA/E Y5.

May 27, 1958 w. G. HoELscHER CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS Filed Aug. 9, 1956 11 Sheets-Sheet 2 IN VEN OR.

B WIM g Arrow/5Y5,

y 27, 1953 w. G. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS ll Sheets-Sheet 3 e 5 f a d i h y 27, 1958 w. G. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS Filed Aug. 9, 1956 ll Sheets-Sheet 4 ATTOEMEYi 11 Sheets-Sheet 6 W. G. HOELSCHER CLAMPING AND ELEIVATING APPARATUS FOR MACHINE TOOLS May 27, 1958 Filed Aug. 9, 1956 y 7, 1958 w. e. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS ll Sheets-Sheet 7 Filed Aug. 9, 1956 wB;. @INVENTOR. I '14 n-rram/eys.

y 27, 1953 w. G. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS Filed Aug. 9, 1956 ll Sheets-Sheet 8 k) 1.4 5 A E /VU //Y II/ /V )I (9); I o o k j s 155 1 1 14s 147 F W///(///////////////////// WWW/1% 127 IN V EN TOR. I591; mm 54% y 27, 1958 w. G. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS Filed Aug. 9, 1956 ll Sheets-Sheet 9 IN VEN TOR.

Arrow/5x5.

y 1958 w. G. HOELSCHER 2,836,086

CLAMPING AND ELEVATING APPARATUS FOR MACHINE TOOLS Filed Aug. 9, 1956 ll Sheets-Sheet lO V H V /.n:&

Q T TOENEY5 United States Patent 6 i CLAMPIN G AND ELEVATDIG APPARATUS FOR MACHINE TOOLS William G. Hoelscher, Cincinnati, Ohio, assignor to The American Tool Works Company, Cincinnati, Ohio, a corporation of Ohio Application August 9, 1956, Serial No. 603,001

14 Claims. (Cl. 77-28) This invention relates to radial drills and has particular reference to an apparatus which provides rapid, precise regulation of the arm movements and clamping mechanisms, utilizing a centralized electrical switch unit mounted on the drill head at the operators station for remote control of the several mechanisms.

A typical radial drill comprises a base having a rotatable column, an arm slidably keyed for vertical motion along the column, and a drill head shiftably mounted upon the arm. The drill head includes a rotating spindle in which the drilling tool is mounted. In setting up the machine to drill a hole in the work piece, which is mounted upon the base, the operator aligns the spindle with the hole center by swinging the arm manually above the work piece in an arc and by shifting the head lineally along the arm. The proper elevation of the spindle is obtained by raising or lowering the arm with respect to the column. When the spindle is precisely aligned, the arm is clamped to the column, a column clamp is actuated to lock the column (and arm) against arcuate motion, and a head clamp is actuated to lock the head to the arm. With the adjustable components rigidly locked, the machining operation is executed by rotating the spindleand feeding the spindle and its tool downwardly into the work piece.

The clamping mechanisms of the conventional drill may be operated either manually or by power, utilizing electric or hydraulic motors which are controlled by manual control means such as levers. To permit the operator to swing the arm with relative ease, the column usually is journalled upon antifn'ction bearings and the arm is carried in a substantially balanced position by the column. However, the ease of arm motion allows the spindle to be displaced from its precisely aligned position in response to relatively light pressure which may be brought to bear, for example, in shifting the manual control means of the clamps and elevating mechanism.

The present invention is directed primarily to an electrical apparatus for actuating an electric column clamp motor and an electric head clamp motor; it is also directed to a motor controlled arm elevating and clamping mechanism. The specific mechanical construction of the column clamp and head clamp does not form a part or the present invention; however, an electrically operated head clamp and column clamp, for which the system is intended, are shown in the co-pending applications of William G. Hoelscher, Serial Nos. 558,253, filed on January 10, 1956, and 571,032, filed on March 12, 1956. The control apparatus of the present application regulates the reversible motors of the head clamp and column clamp, as well as the arm elevating and clamping mechanism.

One of the primary objectives of the invention has been to provide an electrical control apparatus having a centralized group of regulating switches mounted in a control box on the drill head adjacent the spindle, enabling the operator, by remote control, from a centralized station, to actuate the column clamp motor and head 2,836,086 Patented May 27, 1958 clamp motor, and also the control motor of the arm elevating and clamping mechanism. Since the control switches are actuated with very little force, the arrangement eliminates the tendency to displace the arm and spindle from selected position as the elevating and clamping mechanisms are actuated; moreover, the centralized grouping of the switches allows the operator closely to' observe the relative position of the tool and hole center during the clamping and arm elevating operations. The centralized grouping of the switches has the further advantage of increasing speed and precision since it is unnecessary for the operator to move from his control station at any time while setting up the machine and placing the spindle in operation.

A further objective has been to provide, as part of the control box a set of push-button switches (clamp and unclamp) which provide either dual control of. the column and head clamps, or operation of the two clamps independently of one another. For this purpose, the control box includes a clamp selector switch which may be set either for dual control of the clamps or for operation of the head clamp or column clamp independently of one another. Under dual control, a great deal of time is saved in adjusting the arm and head; moreover, the spindle may be set more precisely sincev both clamps may be clamped rigidly as soon as accurate spindle alignment is obtained.

Another feature of the selective clamping system rises from the fact that the control apparatus provides independent cycles of both clamping mechanisms when under dual control, such that each clamping mechanism goes through its complete clamping or unclamping cycle, independently of the other, in response to actuation of either push-button. The independent cycling of the clamping mechanism makes them self-responsive to the push-button signals. clamps be engaged when a signal is sent for dual clamping, only the clamp which is disengaged will be energized through its cycles; if both clamps are disengaged, then both are energized through their clamping cycles.

A further objective has been to provide, as part of the centralized control box, an arm selector switch which is rotated to three positions to raise the arm, clamp it to the column, or to lower the arm. The arm elevating mechanism, which is. controlled by the arm selector switch, in general, comprises an elevating nut rotatably carried in the arm and threaded upon an elevating screw suspended from the top of the column. The nut is driven in forward and reverse directions by the elevating mechanism which includes forward and reverse clutches driven from the main motor of the machine tool. These clutches are shifted by a reversible arm control motor which also actuates the arm clamp as an incident of the clutch shifting operation. The control motor disengages the arm clamp upon shifting the clutches for raising or lowering the arm, and engages the clamp upon disengaging the clutches.

The control apparatus for the arm elevating mechanism, similar to the head clamp and column clamp, also is arranged to complete its own cycle when the selector switch is shifted to raise, lower, or clamp the arm. Thus,

when the selector switch is shifted to move the arm, the.

arm control motor operates through its cycle, then deenergizes itself, while the arm continues to move in. the selected direction. When the selector switch is shifted back to its neutral or arm clamping position, then the.

arm control motor shifts the mechanism back to its neutral position, with the clutches disengaged and the,

arm clamp engaged. This restores the electrical control circuit for again shifting the arm in either direction in response to the movement of the selector switch.

A further objective has been to provide a safety switch For example, should one of the the .gearv train to theielevating nut.

j and cams which which deenerg'izes the main motor the event the operator inadvertently causes the arm to be elevated beyond a predetermined limit, thereby preventing the aeeaosa;

arm. fromistriking the cap at thetop of the column,

with possible damage. to the machine. The control apparatus is so arranged that upon being tripped, the safety.

switch" not only deenergizesthe main motor, but makes it necessary toshift the arm selectorswitch for downward arm motion beforethe main'motor can again be energized; This prevents the operator from accidently starting the main motor with the controls set for arm raising motion when the arm has already reached its'up- 'gperlimit;

Briefly therefore, the present inventionprovides. rapid operation of the column clamp, head clamp and arm clamp, thereby'increasing the productivity of the machine by eliminating manual'efiort onthe part of the operator. Moreover, the centralized controlsystem provides greater power mechanism.

precisioninaligning the spindle since the push-button and directional control, switches are grouped near the spindle'where the exact tool position is clearly visible.

' Thedrawjngs disclose the motor. controlled arm elevating and. clamping mechanism and ,thefcontrol system for regulating the cycles of this mechanism as wellas the cyclesof the column clamp and head clamp motors. As

VJ noted} above, the specific construction of the column V clamp and head clamp has been omitted from the present disclosure. I V

p In the drawings: Y

Figure 1 is a rear elevation of a radial drill equ ippedwith. the. mechanism of this invention.

V Figure" 2 is a fragmentary view of the head and arm as viewed from the front or operators side.

7 Figure3 is an enlarged-sectional plan view taken along line; 3 3 of Figure 1, showing the general arrangement Qfthe. elevating and' clamping mechanism, a' portion of the arm being broken'away to show the arm clamp.

Figure, .4 is anenlar'ged fragmentary rear view taken V Figure, 5 is,a view similar toFigure 4, with the covers Figure 6 is a sectional view taken along line 66 msm;

Figure 7 is a sectional view' taken along line 7-7 of Figure 5, detailing the reversing drive system of the arm elevating mechanism. 7 V

l Figure '8 is a sectional view taken along line 88 of Figure 7, further illustrating the driving systemof Figfrom Figure 1, showing the exterior arrangement of the arm elevating and clamping mechanism; also, the column clamping mechanism. a

nd. cw ina nss anism. i e is ak .i.r9xn..l? a:.

ure 3 and is indicated alongthe line 15-15 of Figure 5.

Figure 16 is a view, partially in section, taken along line 1616 of Figure 3, illustrating thepower drive for the column clamping mechanism.

Figure 17 is a sectionaLview'taken'along line 1717 of Figure 16, illustrating the limit switches of the column clamp motor.

Figure 18 is a sectional view taken along line '18-18 of Figure 17, further illustrating the column clamp limit switches.

Figure 19 is a sectional view taken along line 19-- 19 of Figure 16, showing the gear train of the column clamp Figure 20 is a fragmentary view, similar to Figure 4, showing the arm elevated to the column'cap, with thearm limit switch of the column cap tripped to stop the arm at its limit'of travel; a

Figure 21 isaztop-plan view projected frQniFiguIe-ZD.

Figurell is an enlarged front elevation of. Lhe;.-cen? tralized control boit taken from Figure 2.

Figure 23 is. aside elevation of the control boir pro jected from Figure 22.

Figure 24 is a sectional'view' taken'along Eucl d- 2 4 I of Figure 22..

t General arrangement The'rajdial, drill shown-in Figuresl and] comprises. a base 10'upon which'the worleis mounted and a stamp 11 boltedtothe base and rotatably journalling a vertical column '12. The arm 1-3 is slidably keyed to. the column.

and 'is shiftable vertically by means offa power-driven elevating nut (described later) threaded iupon an'elevating-screw 14 which is suspended from the top, ofthe column. The drill head 15 on the arm' includes a spindle 16 which may be equipped. witha number of different types of tools such as drills, reamers, taps or counter boring tools, depending upon the nature of the work.

. removed to illustrate the interior components of the arm V elevating and clamping mechanism. 7

of Figure 5, showing the motor drive of the. arm mecha-- stump, then the drill spindle is rotatedi a nd fed down- 7 Figure 9 is atragrnentary sectional'view taken along.

linej9-i-9 of Figure 5 illustrating the clutch and brake cams of the arm mechanism.

Figure 10 is a sectional plan view taken along'line cams in their neutral position. In-this view, the brake V cam,..which.is also mounted on the cam shaft, is shown in braking position and the arm clamping cam is shown in clamping position;

10 10 of Figure 9, diagrammatically illustrating the' 'Figure 11 is similar to Figure, 1'0, showing the clutch V cams shifting partially toward elevatingposition, with v [the brake and arm clamp camsshifted to' release posi= tion, V I

.. iFigpre l-2 showsgthe position ofthe parts upon being" shiftedjully. to c'lutch-engaging, arm-elevatingposition;

Figure. 13fjshows the partsshifted to arm. lowering i {position with thebrake and arm'clarnp released.

* jFigure 14 is' a vie w' taken alongline 14-?1'4 ofFigure 5 showing the brake cam, its actuating: linkage, and i e Figure -15 is'an enlarged sectional view of the switches control the 'motofof the=arm elevating In operatingthe machine, as noted earlier, the armis raised orlowered'as required, the head is shifted length wise along the arm, and the arm is'swungradiallyto position' the axis'of the spindle with the hole center. With the spindle centered and the arm clamped, the head isclamped to the arm, the column 'isfclamped to; the

wardly tomachine the hole. 7

As described in detail later, the} arm clamp'is interconnected with the elevating mechanism, such that the" clamp is disengaged in an automatic manner when the elevating mechanism is activated to raise. or lower the arm. The armclamping and elevating mechanism is actuated by the reversible arm control motor indicated'at 17 in Figure 1, which is mounted upon the portion of the arm which embracesthe column. The arm clamp is indicated generally at 18 in Figure 3. "The column clamp, which :is indicated generally at' 20, in Figure 1, is actuated by the reversible column clamp; motor 21 which is also mounted upon the arm near the column.

I The head clamp"(notshownlis driven by a reversible motor 22 mounted in the upper portion of the lead, as indicated in Figure 2.

Powerfor'rotatlng and feeding theldrlll spindle 16 V is supplied by the main motor 23 (Figurefi) ,which'is;

mounted uponan overhanging portion 24 0f the arm and omitted from the drawings;

Figure 25;is an electricaldiagram of the control cit details have been aesaoss The head clamping mechanism is shown in the aforesaid co-pending application, .Serial No. 571,032 and the column clamping mechanism .30 is shown in the co-pending application, Serial No. 558,253. Operation of the head clamp motor 22, arm control motor 17, column clamp motor 21, and main motor 23 is controlled by switches mounted in the centralized control box 26, which is carried on the operators side of the head as shown in Figures 2 and 22-24.

As noted earlier, the present invention is directed primarily to the control apparatus for operating the head, clamp motor 22, the column clamp motor 21,' and the arm control motor 17 which regulates arm elevating and clamping. The arrangement is such that the operator may precisely align the spindle with the hole center in a rapid convenient manner and with very little manual effort. The head and column clamping motors as well as the arm control motor are disclosed in the control circuit of Figure 25, as described in detail later. The control circuit, and most of its components are mounted in the electrical cabinet 27 (Figure l) which is mounted upon the arm alongside the main motor 23.

Arm elevating and clamping mechanism The mechanism for raising and lowering the arm is enclosed in a gear box indicated at 28 at Figures 1, 3 and 7. The power for this mechanism is derived from the main motor 23 driving through a pair of clutches in the gear box which provide forward and reverse rotation of the elevating nut 3% (Figure 3). These clutches are shifted by the arm control motor 17, which in turn, is remotely controlled from control box 26. The gear box is in driving connection with the elevating nut 35 by means of the gear train indicated generally at 3i in Figure 14.

The arm normally is clamped to the column by the clamping mechanism 18, which is connected by a link 32 to the cam-operated lever in the gear box as explained later. The arrangement is such that the arm clamping pressure is applied when the two clutches are in a neutral position, and is released in an automatic manner when either of the clutches is shifted to raise or lower the arm. In other Words, before the arm can be shifted, the arm clamp necessarily must he released.

For controlling the arm elevating and clamping mechanism, the centralized control box 26 at the front or operating side of the drill head, is provided with a directional control knob 33, actuating a rotary select switch, as described later, which upon heir; direction from a neutral arm cl one of the clutches into an same time, releases the arm clamp. selector switch is interconnected in the control circmt as described later. In order to prevent the arm from over-turning under the momentum effect of its gear train, a braking mechanism, also described later, is interposed in the gear train. The brake, which is normally engaged. locks the elevating nut against rotation when the elevating mechanism is inactive, with the arm clamp engaged.

The clutches and other driving components of the elevating nut are best described with reference to Figures 5 to 13. Referring particularly to Figure 7, gear box 28 is bolted directly on one side of the arm 13 and the main drive shaft 34 (main motor 23) is iournalled in its upper portion. The arm elevating clutch is indicated generally at 35 and the lowering clutch is indicated at 36. The clutches are alternately engaged by a yoke 37, which is shifted to the right or left by the clutch cams 38 and 40. These cams are keyed upon a rock shaft 41 which in turn, is rotated in forward and reverse directions by the arm control motor 17. The clutches are of the friction type and are engaged when pressure is applied to them by the yoke 37. The clutches and several other components of the nut driving mechanism are of conventional design and for this reason, need not be described in detail.

As seen in Figure 8, the clutches are mounted upon a sleeve 42 which in turn, is journalled on a pilot shaft 43. Each clutch includes scts of friction disks 44, one set of disks being keyed to the sleeve 42 and the comanion set being keyed to the external clutch drum 45. Each clutch drum includes a driving gear 46 or 47, which transmit power in forward or reverse to the elevating nut 30 through the nut gear train 31 (Figure 14). Power is transmitted to the clutches by a main driving gear 48, which is keyed to the clutch driving sleeve 42. A pinion 5Q, keyed to an extension of the main motor shaft 34, powers the clutch driving gear.

With the yoke 37 in the neutral position shown, both clutches are in neutral or disengaged position and the main clutch driving gear 43 (and its sleeve 42) is free to rotate without driving the nut. The main motor runs continuously while the machine is in operation and transmits power to the spline shaft which drives the drill head as noted earlier. For this purpose, the main shaft 34 in the upper portion of the gear box includes a pinion 51 meshing with a gear 552 which is keyed to a sleeve (not shown) splined shaft 25 being in driving connection with the sleeve and thus rotated continuously by the main motor. The spline shaft and its sleeve are co-axial with the pilot shaft 43 and their adjoining ends are held in alignment by a pilot bearing (not shown).

The transmission for driving the nut comprises the splined nut, drive shaft 53 (Figure 8), journalled in the gear box below the clutch pilot shaft 43. The brake, indicated generally at 54, is mounted on the shaft 53 between a forward nut driving gear 55 and a reverse nut driving gear 56. It will be noted in Figures 7 and 8, that the gear 55, which drives the nut shaft .53 in elevating direction, meshes directly with the gear ofthe elevating clutch. The companion gear 56, which drives the nut shaft 53 in lowering direction, is driven in the reverse direction by a gear coupler 57 mounted upon an idler shaft 58, the coupler having one of its gears 60 meshing with the gear 46 of the arm lowering clutch. A second gear 61 of couple meshes with the reversing gear 56 of the nut driving shaft 53. it will be seen in Figure 7, that when the elevating clutch 35 is engaged, its gear 47 rotates in the direction indicated to drive gear 55 and nut drive shaft 53 in elevating direction; when the lowering clutch 36 is engaged, its gear 46 drives through reversing gear coupler 57 to drive the gear 56 and nut shaft 53 in the opposite or lowering direction.

As shown in Figure 14, the nut gear train, which is driven by shaft 53, includes a bevel gear 62 meshing with a companion bevel gear 63. Companion bevel gear 63 includes a gear 64 meshing with a gear train 65 to the nut 30, as indicated in Figure 3.

The brake 54 (Figure 14) includes a stationary internal brake drum 66 pinned to a lug 67 in the gear box, and a rotating external drum 68, with sets of braking disks 70 connected to the stationary and movable elements. The rotating external drum 68 is normally urged toward the stationary drum 66 by a compression spring 71. The external drum includes a thrust ring 72 engaged by a yoke 73 pivoted as at 74 in the housing, and having a lever end 75 projecting outwardly and carrying a roller 76. A second lever 77 pivoted as at '78 to the gear box, has one end in camming engagement with the roller 76 of the yoke lever, and its oposite end includes a roller 8%) in bearing engagement with the brake cam 81 keyed to rock shaft 41. The brake cam includes a flat 82, and upon rotation, forces the yoke 73 toward the left as viewed in Figure 14, so as to release the brake.

As shown in Figures 5 and 6, the reversible arm control motor 17, which is mounted directly upon the gear box, is connected 'to rock shaft 41 by a worm Wheel 83 keyed to the shaft and driven by a worm 84 keyed to the motor shaft. The gear box includes a vertical housing 85 including bearings 86 which journal rock shaft 41. The worm A is carried on a cross shaft 87 which is portion 193' through which the bolt passes. cludes a lobe 134 which forces the clamping lever SS estates journalled in bearings 88 located in the upper portion 90 of the vertical housing. The lower portion of housing 85 is open to the gear box, as shown irrEigures 7 and 9, for interconnection with asleeve 91 which shifts the clutch yoke '37 and thrust element of the clutches. The sleeve and its yoke are attached to a slide rod 2 shift- I ably. mounted within the gear box 28. The brake cam 81 ismounted below the clutch cams '33 and 40 and its operating lever also projects through the vertical housing 85 for actuation. by cam 81.

The link 32., which actuates the 7 arm clamp i8, is

' pivotally connected asat 93 to a short' lever 94 keyed to to upper portion of the rock shaft (Figures and 15 The link extends across the top of gear box 28 and its opposite end is pivotally connected to a lever 95 of a sleeve 96rotatably journalled in the arm (FigureS). Sleeve 96 includes a cam H which actuatcs' an arm clamping lever 98, lever 93 having a roller 1% presented to the cam. A clamping bolt 161 is pivoted as at H72 "to the end'of clamping levers 98, the arm having a split Cam 97 inoutwardly to clamping position as shown in Figure 3. It will be'understod from this point that when the link is shifted in either direction from the position shown, the

cam is; rotated to unclamp the arm.

. Arm control apparatus The arm control apparatus forms a part of the present invention and controls the cycling of the arm elevating and clamping mechanism. described above. Three limit switches, indicated at A, B, and C in Figures 5 and 15,

are mounted upon the top of vertical housing 85 and.

controls the operation of the arm control motor 17 in s, response to the selector knob 33 ofthe centralized control box 26., Switches A and B each include an actuating arm 106 having a roller 1% presented to a cam 108 fixedto the upper end of rock shaft 41. The switches A and B, in conjunction with the control circuit later described, control the cycles of motor 17.

It will be noted that the limit switch cam 108, the

clutch actuating cams 38 and 4G, and brake cam 81 are all mounted on rock shaft 41. The arm clamping cam 97 is mounted in another portion of thelarm, however;

for convenience, .it is shown in the diagrams (Figures -13) adjacent the rock shaft. ,As shown in these views, the'clutch sleeve ;1 includes a pair of rollers 110, one

. presentedto clutch .cam 38 and second presented to the lower comet) (Figure 9.). ln'the neutral or disengaged POSltlOIhO I SLthC arm elevating,clutches.38 and 40shown arm'clarnpingcam 97 .andbrake cam fil rotate-to release the armclamp arid brake before the .recessilfi engages the roller-iii to shift the sleeve and .clutch yoke 37.

Continued rotation in the directiOnshOWn fin Figure 11,.

shifts the sleeveand. its yoke -to the left, thusengaging the elevating clutch .35 and. causingirotation .ofnut 30 in arm raising direction. .It isto beznoted that the arm clamp and brake will have been released before the clutch is engaged 'so as .tolpreventi any .strain upon the driving mechanisnnf When. control motor 17.is energized nut in the opposite direction through the reversing gears as indicated earlier. 7 In each of the two positions shown in Figures'12 and 13, the control motor 17 is deenergizcd at the limit of its motion by the switches A or B as described later; i

. The third switch C serves as a safety device in connection' with the column lirnitrswitch as described later,

The safety switch C is tripped to a closed position by a cam 114 when the rock shaft 41 is rockedto arm elevating position as indicated by the arrow in Figure 15. As de scribed with reference to the control circuit, the main' motor 23 is deenerzied by a top limit switch '1), (Figure in the event that the arm is elevated to 'a point where it ,is about to. engage the cap 115 at the top of the column. Safety switch C makes it necessary to shift controlknob to arm lowering position before the-main motor can again be energized. a

As best shown in Figure 5, the limit switches A, B, and C are enclosed by a cover 113 mountedupon housing 85. Cable conduits 116 and 117 extend from control cabinet 27 to cover 113 and from the cover to motor 17.

Electric wires pass through the conduits and into elec-v trical. connection with the'contacts of the switches for controlling the motor, as explained later. 7

Column clamp actuating mechanism 7 The column clamp actuating mechanism also operates throught its cycles under-push-button'control and'forms a part of the present invention. The column clampZi) is mounted upon a base portion 118 of the rotatable column 12 and establishes a clamping engagement with-a cylindrical portion of the stump 1 1, so as to clamp the column to the stationary base (Figure 1). The clamping;

mechanism (not shown) is not essential to the present invention. The structure preferably is of the type shown in the aforesaid co-pending application, Serial No.

558,253, noted earlier. j

. The clampis actuated by the square shaft 12% passing loosely through the sleeve 96 of the arm clamp (Fig ure 3). Shaft 12% has its upper end journalled in the column cap 115 (Figure 4) an cl'its lower end journailed in the housing of, the column clamp'zfif Shaft;

12%} is rocked to clamping .or unclamping position by a link 121 (Figures 1 and'l6) located below the arm.

The link has one end pivotaily connected at 122 to anactuating lever 123 which is rocked by the clamp actu:

, ating mechanism. This mechanism, as described later, is driven by the column clamp motor 21.

The opposite end of actuating link 121 is pivotally connected as at to stop theelevating motion',the.;rock"shaftand' cams I rotate back to theposition shown ,in aFigurc 10 to disengageclutch 35 to-apply thearm clamp and brake.

When the motor is energized in the direction to lower the arm as shown. in Fi re -13, .the arm'clamp andf brake 'rerlfirst released, as above, thenlthe-sleeveand its yoke are shifted to thef l'ight asfini cated, so as to en 'gage the'right handrlowering clutch 36, which drives the,

124 to a lever 125 having a hub 126 journalied for rocking motion in the arm. slidably embracing the square actuating shaft 12%, such that the arm (and hub 126') 'is free to shift vertically along the column. l/lovements of link 121 thus impart rocking motion to shaft 12%) for clamping or tin-clamp-y The exact construction of hub 126 has.

ing the column. been omitted since it forms no part of the present invention. r 7

However, it will be noted in Figure 3 that column clampingsh'aft 126 is co-axial Witharm clamping sleeve p a 96 and passes loosely through it. The reversible cob umn clamping motor 21 is driven in clamping and un clamping directions in response to the push-buttonsof the centralized control box 26. As shown inFiguresl6 to 19, motor 21, which is. mounted at the top of new. i

ing 127, includes a vertical'shaft 12% upon which is keyed a pinion 133 meshing with a gear 131 within the Gear 13.7. is keyed to a shaft 132 journalled the housing and having keyed .to it a pinion 133 mesh The gear sector is secured 1 housing.

ing with a gear sector 134. upon a vertical shaft 135 having opposite ends proiect-. ing beyond the upper and lower walls of the housing. 127.

(Figure 16). {The actuating lever 12.3 is mounted upon. the lower portion of'thisshaft and preferably includes a split portionltraversed by a screw 136 which. .drawsf Hub 126 includes a square hole.

lobe 143.

the split portion into clamping engagement with shaft 135. This arrangement permits the actuating lever to. be adjusted upon the shaft to the proper operating angle. The actuating lever 123 is further secured upon the shaft by a nut 137 threaded upon a stud portion of the shaft.

In the position of parts shown in Figure 19, the column clamp is engaged upon rotation of the pinion and gear train to the unclam-ping position, as shown in broken lines, thus rocking the square shaft 12% to unclamping position through link 121 and actuating lever-s 123 and 125. It will be seen in Figure 19, that the gear train provides a reduction ratio from the motor pinion 13% to the gear sector 134.

The clamping motor is deenergized at the limits of its stroke by the limit switches E and F mounted on top of housing 127. These switches, as described with reference to the electrical circuit cause the motor to drive through its clamping or unclamping cycles and to be deenergized at the limits of travel in response to signals from control box 26.

The limit switches are actuated by a pair of cams 138 and 140 mounted one above the other upon the upper portion of shaft 135 of gear segment 13d. To provide adjustment for the limits of motion, each cam includes a split hub 141 traversed by a clamping screw 142 which compresses the split portion and clamps the cam at the required setting on shaft 135. Each earn is generally in the form of a sector and each has a switch tripping The lobes of the two cams reside in opposite positions, such that the two switches alternately are tripped at the limits of clamping motion of shaft 135.

The switches E and F, which are identical, are of conventional design and each includes an insulated switch block 144 having a slidably mounted switch plunger 145 which carries a contactor 1 6. A compression spring 147 normally urges each plunger outwardly against an actuating lever 14% (one for each switch plunger). The actuating levers have their ends pivotally mounted upon a stub shaft 156 and each includes a roller 1S1 intermediate its length which bears against the arcuate surface of a respective cam. Each switch arm includes a tension spring 152 having one end anchored to the swinging end of the lever and its opposite end anchored upon a pin 153.

The position of the parts shown in full lines in Figure 17 corresponds with the clamping position shown in Figure 19. In this position, the lobe M3 of the lower cam depresses the plunger of the lower switch F while the upper switch E is in normal position. Upon shifting to unclamping position, as indicated in broken lines (Figures 17 and 19), the plunger of the upper switch E is depressed while the lower one F assumes its normal position. The contactors of these switches and their motor controlling function is explained in detail with reference to the electrical circuit.

The switching mechanism is enclosed by a cover 15% mounted upon the top of housing 127. The electrical conductors extend from the switch terminals through an opening in the cover to the control cabinet 27 by way of the T-shaped conduit (Figures 3 and 4) which also extend to motor 21.

Column safety mechanism Referring to Figures 4-, 20 and 2i, the column closure cap 115 at the upper end of the column is provided with an outwardly projected casing 156 in which is mounted the safety limit switch I) which deenergizes the main motor 23 when the arm reaches its upper limit of motion. The casing is provided with a cover 157 enclos ing the switch. The switch includes an actuating arm 158 having a roller 16% at its outer end which is engaged by the tapered end 161 of a stud 2152 rising upwardly from the arm. In the normal or working range of the travel, the stud 162 projects upt ardly in alignment with a hole 163 in the bottom wall of the switch casing 156 with the switch arm extending horizontally in normal position. The contacts of limit switch D are interconnected with the control circuit as explained later. in the upper limit of arm travel shown in Figure 20, the switch contacts are open and the main motor 23 is deenergized.

Centralized control box Referring to Figures 22-24, the centralized control box 26 consists of a housing 164 secured to one side of the drill head at the operators side. The front panel 165 of the control box is provided with two rotary selector switches indicated at G and H and two push-button switches indicated at l and K. Selector switch G is actuated by the knob 23 and selector switch H is actuated by knob 166. Each knob has three positions as in dicated.

When the selector knob 166 is in the dual position shown, the control circuit actuates both the column clamp motor 21 and head clamp motor 22 concurrently in response to actuation of the clamp or unclamp push-buttons I or K. When knob 166 is indexed either to the column or head position, then the clamp or unclamp buttons actuate only the selected clamp upon being depressed.

As noted earlier, the arm clamp is actuated in an automatic manner co-incidentally with the actuation of the elevating mechanism. Thus, in the indicated position of knob 33, the arm clamp is engaged and the elevating mechanism is inoperative. Upon being shifted to raise or lower position, the arm is unclamped and the raising or lowering clutch is engaged as explained earlier.

As shown in Figure 24, the body of each rotary switch G and H resides within the housing and includes terminals 167 which are interconnected in the control circuit. The switches are of conventional design and are clamped or otherwise secured to the panel 165 in the usual manner. Each knob 33 and 166 includes a fiat gripping portion 168 for convenient operation and the exposed edge of the fiat carries the arrow which registers with the indications on the panel.

As viewed in Figure 23, the body of each push-button switch I and K also includes terminals 170, likewise interconnected in the control circuit. The body of each switch, similar to the rotary switches, is clamped or otherwise secured in front panel 165. The construction of the switches is conventional and has not been illustrated.

Referring to Figure 23, the side of the control box includes a side panel 171 for mounting and start and stop push-button switches L and M which control the main motor 23. These switches are also interconnected in the control circuit.

Electrical control system The electrical circuit shown in Figure 25 controls the operation of the main motor 23, column clamp motor El, head clamp motor 22, and arm control motor 17 in response to the manual operation of the selector switches G and H and push-buttons J and K of the control box as. The relays are mounted in the cabinet 27 of the arm, while the several limit switches shown in the control circuit are those which are mounted upon the rock shaft 41 and of the arm elevating mechanism and column clamping mechanism.

The power lines and control lines of the circuit comprise the cable loop 172 (Figure 1) from the control cabinet to the top of the head, and cable loop 173 from the column to the drill head. Power is conducted to the several motors and control relays by a power cable (not shown) extending from the base of the machine through the column and connected to slip rings at the top of the column, thence by way of brushes in contact with the slip rings to the two cable loops. For the sake of simplicity, the cable loops have been omitted from the diagram.

ssess;

5 Generally described, the control circuit comprises sets of relays for each of the three reversible control motors V of the column, head and arm. The main motor, which is non-reversible, is started and stopped by a single relay.

Referring to Figure 25, electrical energy'is' supplied to the circuit from the three-phase power lines 174 which are connected by branch lines 175 to the main motor,

This deenergizes. the HC relay and opens its motor con- Relay HC tacts to deenergize the head clamp motor. 7 includes a normally closed interlock, contact HC in the line 186 which leads to the head unclamp relay. HU

and to the column, head and arm control motors. The

control circuit is energized at lower voltage by a transformer 176 having its primary winding energized by the branch .power lines 177. The secondary winding of transformer is connected to the supply lines 178 and 18% of the control circuit.

For simplicity, the circuits of the. several relays are shown directly across the two supply lines 178 and 1% in a way which conforms to the relay designation in com mon use. The relays and their contacts are not shown physically connected; however, each relay and its concontactsactuated by relayCC (column clamp) are indicated as-CC in the control lines and power lines. The various switches and components of the control circuit line-187 which leads to the head clamp relay HC and? column clamp relay CC. This contact insures operatacts have a corresponding designation, for example, the

are all shown ina neutral position corresponding to the setting of the selector knobs ofFigure 22.

7 Head and column clamp circuits Assuming that the operator has centered the drill spindle and wishes to clamp both the headtand column,

he may set the clamp selector switchH (knob L66) to dual position, then depress the clamp button switch Selector switch H includes two'conta'cts 1 79 and 185.

The-clamp push-button switch is. normally'open and is interposed in branch' line 181 extending from supply line 178, through the column clamp relayCC through' selector contact 179 to the opposite supply line 130. As-

suming that'the column clamp isunclamped at this time, limit switchE in line-.181 will be closed as indicated;

therefore, relay CC willbe energized. Y Upon being energizedfrelay CC opens its normally closed interlock,

contact'in line 182;whieh leads to the unclainp relay CU so as to prevent the unclamp relay from being energized.

The unclamp relay also includes a normally 'closedinten lock contact CU in line 181 of relay CC. 'In addition, the

two relaysare interconnected: by a mechanicalinterlock 183 indicated bythe broken line to prevent simultaneous actuation. a l

Upon being energized, a relay CC closes its motor contacts} CC power branch lines 175 which energize'the' columnclampmotor 21 in clampingdir'ection. As the motor engages the column clamp, the cams of the column clamping mechanism open limit switch E of line 181 andicl'ose limit switch F in line 182. When limit switch E opens it deenergizes the relay CC, which opens'gmotor' contacts of branch lines 17S'to stop the column clamp motor. Relay CC at this time closes its contact CC in line 182 and thus sets up a circuit forenergizing unclamp relay CU when the unclamp push-button later is depressed.

Since clamp selector switch H is set .for dual operation. the head clamp is also engaged when the clamp push- 7 button switch K is closed. For this purpose, a branch line 184 extends from supply line 178 to energize head clamp relay HC; The headeclamp' mechanismtnot shown) includes the. limit switches N and O, similar to the switchesE and Fas shown in the co-pending application. With the head unclamped, limitrswitch "N of the head clamp mechanism is closed'and limit switchO-is open as shown. Accordingly, the clamp push-button K' will simultaneouslycnergize head clamping relay 'HC 'byway of line 184, through'the closed second contact of selector. switch H, thus completng thecircuit from supplyline 178 to supply line180. Upon being ener- I gized, relay 'HC closes itsmotor contacts 1 1C in power line 186 to deenergize relay HU, causing its motor con branch lines 1 to drive the head clamp' motoriinlclajmpingadirection; At final limit, jthe head clamping me'cb' anism opens limitswitchN and'closes limit switch 0.

' button switch K momentarily 'isiclosed.

or relay HC fails to-close upon momentary operation f of the switch, then holding contact CC of relayCC, or, holding contact HC in branch line 184 will complete the circuit to both relays, both' holding contacts being in common connection with both relays.

to prevent the relay from being energized; a mechanical,

interlock 183 also interconnects the two relays.

It will be noted that the columuiclamp relay .CC in.- cludes a normally open holding contact CC in branch tion of the column and head clamp mechanism when pushit selector switch H is shifted to the column-position, then its contact 179 is shifted to a second closed position (contact 183) and contact is opened. Accordingly,

upon actuation of the clamp switch K, relay CC wilI be energized, asdescribed above, to clamp the column, but relay HC will not be energized. 1

If selector switch H is shifted to the head position, then its contact 179 will be opened and its contact 18 5 will be closed in its second position (contact 190). In setting therefore, the column clamp relay CC will remain de energized and only the head clamparelay HC will be energized to clamp the head when switch K is closed.

Column and head unclamping If the column and head are clamped and it is desiredito unclarnp bothof them, then selector switch H is placed in the dual control position and the unclamping push-button I momentarily is depressed. This completes the circuit motor rotation in unclamping direction. At the limit of unclamping motion, the column unclamping mechanism opens its limit switch F to deenergize relay CU and open 7 the reversing motor contacts CU of the power reverse.

lines." V i l 1 Since the selector switch I-I is in its dual position, it will a also signal the head unclamp relay HU by Way of'branchline 186, through theunclamp contactO (now closed) and by way of branch line 192, through unclamp switch 7 1, or through the holding contact CU (nowclosed) of line 193. A holding contact HU in line 1 86, now closesto keep relay HU energized until the end of the cycle, The head unclamping relay HU also closes, its motor contacts HU in the reverse power lines 191 to the head clamp motor. The head clamp motor then. operates the head mechanism in unclamping direction until, at the limit of motion, the head'me'chanism opens limit switch 0 in tacts to open and deenergize the head clamp motor. At this time, the companion limit switch N of the head clamping mechanism closes to set up the circuit for motor rotation in head clamping directi operation of the. clamping button.

If selector switch H is shifted to the column positionthen the above described circuit will be completed to the column unclamp relay CU, through contact 179 to its second point 188 of selector switch H. Since the'contact' 185 of the selector switch H. is now opened, the circuit will not be completed through the head unclamping relay HU; hence, the column. will be unclamped but the head will remain in clamped position. 7

If relay CC on upon subsequent Q asaaose 13 in a similar manner, it the selector switch H is shifted to its head position, then its contact 179 is opened and its companion contact 185 en gages point 190. Accordingly, when the unclamp button I is depressed, the circuit is completed only to the head unclamp relay HU to unclamp the head, while the column remains clamped.

Arm control As noted earlier, when the arm selector switch (knob 33) is in intermediate position, the arm is clamped to the column and the clutches of the arm elevating mechanism are disengaged. In this position, brake 54 is engaged to lock the elevating nut in stationary position. When the selector switch is shifted from the intermediate position, either in the arm raising or lowering direction, then the arm clamp is disengaged by operation of arm motor 17, which rotates rock shaft 41 (Figure 15) in the direction indicated for raising or lowering.

Upon being rocked to its unclamping limit of motion, the rock shaft trips the limit switches A or B, either of which conditions the control circuit to deenergize the arm clamp. At this time, the rock shaft also engages one or the other of the clutches 35 or 36 to drive the arm in the indicated direction. The elevating mechanism, through the main motor 23, continues to drive the arm in the selected direction (with its main motor 17 deenergized) until switch G is shifted back to the intermediate arm clamping position. At this point, the control circuit reverses the arm motor 17 to rotate rock shaft 41 back to the intermediate position, thus disengaging the clutches, setting the brake, and engaging the arm clamp.

Since the elevating mechanism is powered from the main motor 23, it is necessary that this motor be energized before it is possible to raise or lower the arm. Referring to the diagram of Figure 25, the main motor is energized by depressing start button L (Figure 23) in branch line 194 so as to complete the circuit through .motor relay MM across supply lines 178-18il. Upon being energized, relay MM closes its holding contact MM in line 195, which shunts the start button to keep relay MM energized after the start button is released. Upon being energized, relay MM closes its motor contacts MM in the power lines 175, which energize the main motor.

it is to be noted at this point, that the column upper limit switch D includes a normally closed contact 1% which completes the circuit to relay MM. If the arm is elevated beyond its limit, contact 196 will be opened by stud 162 to deenergize relay MM and to stop the main motor before the arm contacts the column cap. When this occurs, the main motor can be restricted only by shifting selector switch G to its arm lowering position, as explained later.

As shown in the diagram, limit switch A (Figure 15 includes a normally closed contact 197 in branch line 198 and a normally open contact 2130 in branch line 201. These contacts are mechanically interconnected as indicated by the broken line. Limit switch B also includes two contacts 292 and 203 which are mechanically interconnected as indicated by the broken line. When the cam and switches are in the neutral position shown in Figure 15, the contacts of the switches are in the position shown in the diagram.

The selector switch G also includes two contacts indicated at 204, and 205, which are mechanically interconnected, as indicated by the broken line. When selector contact 2% is in its intermediate or clamping position (or in its elevating position) its companion contact 2135 is open as indicated; when selector contact 294 is shifted to arm lowering position, then its companion contact 205 is closed. This completes a circuit for energizing the main motor in the event that it has been deenergized by the safety limit switch D of the column cap. This arrangement permits the main motor to be energized only by shifting selector G (contact 204) to arm lowering This Arm raising When selector switch G is shifted to arm raising position, its contact 2% completes a circuit from supply line 178, branch line 266, through raising relay R, to supply line 1%. Relay R then closes its contact R in branch line 198, through normally closed contact 197, through normally closed interlock contact LU, through the up relay RU to supply line 139. Relay RU then closes its motor contacts RU in power lines to drive the arm control motor 17 in arm raising direction, causing rotation of the rock shaft as indicated at Figure 15. As the rock shaft rotates, it rotates the clamping cam 97 from the intermediate clamping position (Figure 10) thus releasing the arm clamp. The unclamping cycle continues until cam 168 (Figure 15) shifts the limit switch A to its second position, thus opening normally closed contact 197 and closing normally open contact 200.

When contact 197 opens at the end of the cycle, relay RU is deenergized and the motor contacts RU are opened to deenergize the arm control motor. At this point, the elevating clutch is engaged and the brake is disengaged, therefore the arm will continue elevating (with motor 17 deenergized) so long as the selector knob remains in arm raising position.

When selector switch G is shifted back to neutral, arm motor 17 is rotated in reverse to shift the limit switches back to the position shown in Figures 15 and 25. When normally open limit switch 290 (branch line 291) closes at the end of the cycle, it establishes this neutralizing circuit. For this purpose, there is provided a holding contact RU in branch line 207 which by-passes relay RU; there is alsoprovided a holding contact R in branch line 265:3. Contact R energizes a holding relay HRR in line 216. Holding relay HRR includes a holding contact ERR in line 207. These holding contacts (which are now closed) open when contact 197 (limit switch A) opens at the raising limit of motion.

Since contact 200 (limit switch A) now closes, a circuit is established from supply line 178, to the lowering relay L for motor reversal. This circuit is by way of branch line 281, closed contact 200, through normally closed contacts R and L of line 211 (R and L now being deenergized). The circuit is completed by line 212, line 213, normally closed contact 203 (limit switch B) to line 214. The circuit is completed through normally closed line 215, and line 198, to supply line 180. Upon being energized, relay LU closes its motor contacts LU in reverse power lines 191 to drive the arm motor in arm lowering direction as indicated by the arrow in Figure 15.

When the normally open contact 290 (limit switch A) closes for the neutralizing cycle as above described, the motor continues in reverse until the rock shaft returns to its neutral position to open contact 260 and close contact 197 of limit switch A. This deenergizes relay LU, causing it to open its motor contacts LU and stop the arm motor with the rock shaft at neutral, both clutches being disengaged and the arm clamp engaged. The limit switches and relay contacts are now in the position shown in the diagram.

Column limit switch As explained earlier, the column limit switch D prevents the arm from contacting with the column cap. As shown in the diagram, the limit switch includes a normally closed contact 1% and a normally open contact 216 in lines 194 and 217. If the arm shifts plunger 162 upwardly, contact 216 closes and contact 196 opens. Accordingly, the main motor relay MM of line 194 is deenergized to open the main motorrelay MM of line 175. Since the main starting switch is interposed in line 194, the main motor cannot be started by depressing main starting switch V normally V L; instead, it can be started only by shifting selector switch G to the arm lowering position. V

For this purpose, the selector switch includes the second contact 205, mechanically connected to contact 204, as indicated by the dotted line. When contact 204. is shifted to raising direction, its companion contact 205 is opened; when contact 294 is shifted to loweringposit-ion, its companion contact 205 closes. Accordingly, a circuit is established from supply line 178, branch line 218, closed contact 295, sa fety switch C, and the closed contact 21s of the column limit switch- D. Thisstarts the main motor; however, the arm elevating mechanism will have been conditioned for arm lowering, causing the main motor to begin lowering the arm when the motor starts. -As-the arm lowers, it-closes contact 1 95 and opens contact 216 of the column-limitswitch to place-the mainmotor under the control of its-startandstop-switches Land-M.

As nomd earlier, safety interlock switch C is normally closed and is; opened by itscam whenrock-shaft 41 rotates to elevating position. ltsrpurposeis to guard against damage in. the remotecontingencyof failure in thecontrol circuit. For example, such failure may possibly cause the arm to-continue elevating when selector switch G is shifted to lowering-position. Inihis-case,therockshaft will have been shifted to elevating position and interlock switch. C will be open; =therefore eventhough contact-2% of selector G is' closed, switch C will be open-to deenergize'the mainmotor at the upperlimit of arm travel.

' .Al mlowering a through closed contact 263 (limit switch B) through interlock contactRU and through relay LU, branch lines 215 and 198 to supply line 180. Relay Lalso closes a contact Lin branch line 224 toenergize relay HRL. Relay LU also closes motor'contacts LU in reverse power lines 191 to energize arm motor ,17 .in the arm lowering direction... Relay RU and LU are mechanically interlooked as at 183. i V

Relay LU also opens its interlock contactLU (line 29%) and closes its holding contact LU in branch line 222 V to energize the holding ,relay HRL in line 223. Relay HRL in turn closes its contact HRL in branch line 222 'whichalso includes the contact LU novclosed by the energized relay LU. Thecircuits of branch lines 222 and 224- thus establish a holding circuit whichkeeps the relay LU ener ized until motion of the rock shaft in the unclamp direction is completed.

'At the limit of rock shaft motion, normally closed contact 2433 (limit switchrB) "opens to deenergize relay LU,

thus opening the motorcontact LU ,to'deen'ergi zethe arm motor and to d energize the holding circuit .of branch line 2.22 and'224, causing 'holding relay HRL also to be deenergizedf Since thearm holdings clutch is engaged, the" arm will continue in its downward motion solong as the selector contact 204 is: shifted in its lowering 'position to keep relay L energized. p 7

Upon rotating to its limit in, the-lowering direction, the rocl .shaf t also closescontactfZibZ (limit s'tvitch B) 1 in line 2,255 This establishes a circuit for shifting the v clamp rnotor and rock shaft back to the neutral or damping position when selector switch G shifted to cram nan va en os'ition. is occurs,

relay L is deenergized,- closing its open contact in line 225. The neutralizing 1r u lt is'completed to relay RU irornsupply line 1'73,

2 ;d:contact cs2 limit switch B) lines 225,. contacts 'R and L, which are nowclosed.

The circuitis completed through branch line 226, contact 197 (limit switch A), line 1-93,. closed contact LU, through relay RU to supply line 180. 'Relay RU now closes its motor contacts RU in lines l75 to drive the motor and rock shaft toward neutral. V

Upon reaching --the neutral position, the rock shaft opens contact 2&2 (limit switch B) and thus deenergizes the relay RU and the arm motor to decommission the driving mechanism and to stop the :rock shaft in' its neutral position with ;tl 1e arm clamped. The contacts of limit switches AV-and Bare now in the position shown in the diagram and the circuit is ready for the next raising or lowering operation.

Having described rny invention," I claim:' 1 l. A centralized control apparatus for, a radial drill having a column, a column clamp, an arm, a shiftable, power-driven arm elevating mechanism, ,a head on the 7 arm, and a head clamp mounted in said'rhead, said control apparatus comprising, a reversible arm control motor connected to thearnrelevating mechanism, a reversible column clamp motor connected to the column clamp, .21' rcversible headclamp motor connected tothe head clamp, a centralized control unit mounted on the head, a manually operated arm control-switch on said-control unit, said switch havingan intermediate position having an armraising positionand havingan arm lowering position, a manually operated clamp selectorswitch in said control unit, said switch having a dual clamping position,

having a column clamp position, and having .a head clampposition, aclamping switch in said control unit, an unclamping switch in said control unit, a control system electrically interconnecting said motors ,andrsaid switches of the controlunit, said arm control motor normally residing in 'an interriiediate position disengaging f the shiftable arm elevating mechanism, said control systern energizing the arm control motor'in forward or reverse toshift the power-driven elevating mechanism in respective directions to raise or lower the arm in response to actuation of the arm selector switch from said intermediate position to 'saidraising or lowering position, the

7 control circuit interconnecting the column clamp motor and head motor when said clamp-selectorswitch is in said dual clamping position, the control system .ener gizing both of said motorsin forward or reverse direction toengage or disengage the head and column clamps upon actuation of said clamp or uncla'mp switches, the controlsystem actuatings aid motors individually in forward ior reverse directions in response to actuation of the clamp or unclamp switch, when saidselectorswitchis j iblelhead clamp motor connected .to the head clamp ior motors in forward or reverse direction to engage or disshifted to saidtcolumn clamp or head clamp position 1 2. A control apparatus for a radial drill havinga column, a column clamp, a head, and ahead clamp mounted in saidhead, said control apparatuscomprising, a reversible column clamp motor connected to the column clamp, for clamping and unclamping the same fa reversinterconnecting the column clamp motor and head mot or whensaid clamp selector switch is in said dualclarnping; position, the controh'system energizing both *ofqsaid engage the head and column clamps upon'actuation' of said clamp orunclampswitch, thecontrol systemactuating saidmotors individually in forward. or reverse directions in response to actuation of theclamp -or unclamp switch when said selector switch is shifted to saidv column clamp or head clamp position. 1 v I p A control apparatus for a radial drill having a assepee 17 column, an arm, a shiftable power-driven arm elevating mechanism, and an arm clamp engageable with the column, said control apparatus comprising, a reversible arm control motor, a manually actuated arm control switch electrically connected to said motor, said switch,

normally residing in a neutral position and deenergizing said arm control motor, said switch energizing said motor in forward or reverse directions in response to actuation of the switch in either direction from said neutral position, driving means connecting said motor to said arm elevating mechanism and to said arm clamp, said driving means normally residing in a neutral position, said driving means engaging said arm clamp in said neutral position, said driving means disengaging said arm clamp and driving the said elevating mechanism in arm raising or lowering direction upon being shifted in respective directions from said neutral position by operation of said reversible arm control motor, a pair of limit switches in electrical connection with said motor, switch actuating means in driving connection with the motor and engageable with said limit switches at the limit of motion of said driving means in arm raising or lowering direction, said limit switches deenergizing said arm control motor at said limits of motion of the elevating mechanism in arm raising or lowering position, whereby the mechanism continues raising or lowering the arm with the arm control motor deenergized.

4. A control apparatus for a radial drill having a column, an arm, a shiftable power-driven arm elevating mechanism, and an arm clamp engageable with the column, said control apparatus comprising, a reversible arm control motor, a manually operated arm control switch, said switch normally residing in a neutral position, a control system interconnecting the said switch and motor, said control system energizing said motor in forward or reverse directions in response to actuation of the switch in either direction from said neutral position, means coupling said motor to said arm elevating mechanism and to said arm clamp, said coupling means normally residing in a neutral position and engaging said arm clamp and disengaging the elevating mechanism, said coupling means disengaging said arm clamp and driving the said elevating mechanism in arm raising or lowering direction upon being shifted in respective directions from said neutral position in response to said arm control switch, a pair of limit switches in electrical connection with said motor, switch actuating means in driving connection with the coupling means and engageable with said limit switches at the limit of motion of said coupling means in arm raising or lowering direction, said control system deenergizing said arm control motor in response to tripping of the limit switches at said limits of motion of the coupling means, said control system energizing said motor in a direction to shift the coupling means back to said neutral position when the arm control switch is shifted back to said neutral position, said control circuit deenergizing said motor when the coupling means is shifted back to said neutral position, thereby to decommission the elevating mechanism and to engage the arm clamp.

5. A control apparatus f r a radial drill having a column, an arm, a shiftable power-driven arm elevating mechanism, and an arm clamp engageable with the column, said control apparatus comprising, a reversible arm control motor, a manually operated arm control switch, said switch normally residing in a neutral position, a control system interconnecting the said switch and motor, said control system energizing said motor in forward or reverse directions in response to actuation of the switch, in either direction from said neutral position, a-

clamp and disengaging the elevating mechanism, said rock shaftdisepgaging said arm. clamp anddriving the.

said elevating mechanism in arm raising or lowering direction upon being rotated in respective directions from said neutral position in response to said arm control switch, a pair of limit switches in electrical connection with said control system, switch actuating means connected to said rock shaft and engageable with said switches, said switch actuating means tripping said switches at the limit of rotation of said rock shaft in arm raising or lowering direction, said control system deenergizing said arm control motor in response to the tripping of said limit switches at said limits of motion of the rock shaft, said control system energizing said motor in a direction to rotate the rock shaft back to neutral position when the arm control switch is shifted back to said neutral position, said control system deenergizing mechanism and engage the arm clamp.

6. A control apparatus for a radial drill having a column, an arm, a head, and a power-driven elevating mechanism including shiftable coupler means for driving the elevating mechanism in arm raising or lowering directions, said control apparatus comprising, a reversible arm control motor, a control unit mounted on the head, an arm control switch in said unit having a shiftable element for manual operation thereof, means electrically interconnecting the control switch with said motor, said switch normally residing in an intermediate position and energizing said motor in forward or reverse directions in response to movement of said switch actuating means in respective directions from said intermediate position, means connecting said motor to the shiftable coupler means of the elevating mechanism, whereby the elevating mechanism is driven in arm raising or lowering directions in response to the position of said arm control switch, a pair of limit switches in electrical connection with said motor, switch tripping means in driving connection with said motor and engageable with said limit switches, said limit switches deenergizing said motor independently of the selector switch at the limits of motion of the shiftable control means of the elevating mechanism, whereby the said mechanism continues raising or lowering the arm with the arm control motor deenergized, and arm limit means residing at the upper portion of the column and interconnected with said power-driven elevating mechanism, said limit means engaged by the arm at the limit of travel thereof and decommissioning said elevating mechanism.

7. A control apparatus for a radial drill having a column, an arm, a main motor, an elevating mechanism in driving connection with the main motor and including a shiftable coupling device for driving said mechanismin forward and reverse directions thereby raising or lowering the arm along the column, said control apparatus comprising,,a reversible motor in driving connectionwith said coupling device, said motor shifting the coupling device to said forward and reverse positions, an arm control switch having a shiftable element for manual operation thereof, an electrical control system interconnecting said reversible motor and control switch, said control system energizing the motor in forward and reverse directions in response to actuation of the arm control switch, limit switch means in electrical connection with said control system, a switch actuating element in driving connection with the reversible motor, said switch actuating element tripping said limit switch means at the limits of motion of said shiftable coupling device, said control system deenergizing the motor at said limits of motion in response to the tripping of said switches, an arm limit switch mounted on the column and electrically interconnected with said main motor and normally energizing the same, said arm engaging and tripping the arm limit switch at a limit of arm travel and thereby deenergizing the main motor and elevating mechanism in response to the tripping of the arm limit switch. 

